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Dinoflagellates.
These are my findings on this persistent algae and they may not apply exactly to all since there are many types.
After 1,5 years and having tried all of the usual methods and then number of my own I'm getting closer to be an expert.
I got them from a colossal tank and they are visible there if you look for them, but are kept in check by something unknown.
Dinos are extremely successful in the wild and can grow to epic proportions called red tides killing fish and inverts in big numbers with their toxic soup.
They can also sense bad times ahead and create cysts that lie dormant until the conditions are right again.

My tank and I
It's a 420g system lit with three 250W Mh and four 80W actinic T5. The sump is lit with a single 250W Mh.
There are four Tunze stream pumps and a big Eheim return pump. Deltec skimmer and calcium reactor rated for my tank. Bio pellet, carbon and GFO reactors. I have over 10 years in the hobby.

Light color
At 14K Kelvin the dinos grow well.
Under 20K Kelvin bulbs wich is very blue the dinos grow just as well, but are less visible since the color of the light does not bring out the natural brown as much.
I ran 14K and 20K Kelvin, 250W bulbs at the same time just to find out if color range or bulb age matter.Light intensity
The dinos do not like very intense light and usually there is less of them there than in darker spots.
Still they do not grow in fully shaded areas so there is an intensity range they prefer.Dark periods.
I turned the lights off for three days and resumed with 5 hours a day. This was just like hitting the pause button. The skimmer did not skim any more and detritus in the water column did not increase. This was totally useless method in my case. I kept doing the 5 hours light period for two weeks. The dinos did fine before, during and after this test.

Current
I have not seen any difference between high and low current areas except where the current is high enough to blow the dinos right off.

Water changes
Dinoflagellates love water changes and not doing them will for sure make the dinos suffer. Still there is a drawback. I do 25% water changes monthly, but twice I have skipped doing them.
On the first occasion it was for two months and I lost a lot of corals and the dinos did not go away. The second time I had to try this method again and on the fifth week much of the dinos had left and I was pleased with the progress, but after six weeks the dinos in my corals started to leave as well, some corals died while others only lost the youngest growth or tips. There is a very thin line here and I do not recommend this if you have cherished Acroporas.
When I switched from standard TMC mix to full strength Red Sea Coral Pro I had couple of months of amazing coral growth and great colors. At the same time I switched out my Mh bulbs to more yellow ones.
This was when the dinos appeared in numbers and the growth stopped in many of the corals, but not all. Later I realized what I had thought for months to be diatoms on the sand was actually dinos.

Feeding.
I cut the feeding down by half for two months and it had no effect on the dinos. I felt the fish were starving so I went back to normal feeding wich is not much by the way.

Cleaning.
A good skimmer is a must. Without one I think my tank would be a real mess or worse.
Blowing the dinos off the rocks may keep them from settling in and grow into clumps. This could be most useful next to corals were the algae could have a chance to smother a delicate coral. Doing this every few hours can be a real pain though.
The most effective method to remove large amounts at a time is to turn off the pumps, blow off the rocks and siphon the sand. You can siphon the sand twice a week and get each time amazing amounts of gunk that is clearly dinos. I spent a lot of time keeping my tank super clean, but that did not have any long term effect.
Filter socks are very helpful and will collect a lot of dinos both on the inside and as well on the outside if the lighting conditions are right. After two or three days they can not take more.

Growth rate.
I think they may be self regulating by some unknown parameter since they have never crossed certain density and in my case I'd say I have a mild to average dino problem. It never got epic and never got to acceptable.
I have had Cheatomorpha in my sump for almost a year that has never been harvested and hardly grows.

Corals
Coral growth is hampered by the dinos. I think it's the toxic soup they produce.
At times when there have been less dinos the corals show clear signs of good growth, better polyp extension and better health.
Some of my sps corals have been doing quite good for the duration while others are clearly affected by the dinos.
LPS and Montipora are doing fine and are less effected than the usual more difficult corals.
Coraline only grows in well shaded areas the dinos do not like.

Temperature.
I tried to run the tank at several temperatures and that did not leave a dent in anything.

Ca, Alk, Mg, Nitrates.
My tank has both had periods of low alkalinity and low calcium and at that time I though that had something to do with it, but having perfect parameters does not make dinos grow any less.pH
I raised the pH of the tank to about 8.4 for three days using kalkwasser without any positive effect. I had to keep the dosing to a steady stream to keep the pH up. The amount was way more than the tank needed and all of the pumps needed maintenance after.Ferric Oxide. GFO.
For a few weeks I used a few pounds of the stuff and it did not help in any way make the tank look better.Carbon
I think it's useful for the tanks health, but not in a way that you will see any changes.Bio Pellets and Vodka.
I had dinos before and after so they do not solve anything.Algae X
This is not available or has been imported to my contry before so I'm certain to have big problems with customs or need to pay big buchs to have it tried and tested and hopefully accepted in months or years even.

I'm certain Dinoflaggelates change the chemistry of your tank in a way most of it's inhabitants are affected in a negative way. There are a number of methods some reefers have been succesful with while others have not. If you have a small tank, try some of them and restart if you are not successful. If it's a big tank and restart is not an option prepare to lose some corals and be aggressive in your battle against this devil.

I hope this will help someone.DNA

I agree with almost Everything. I have struggled with dinos 7 times, and tried Everything. My brief conclusions is:
1)Algenex works, but the dinos will often be back and the corals suffer some from algenex.
2) cut off the light works but only for the moment. it will be back
3) Probiotica does not work
4) Rising ph is difficult and has no clear effect. I have red some studies that tell the counterpart but i doubt...

The only cure i succeded with is to eliminate all the sand, as it Always start there. Then, rinse the sand in H20 ands replace after one week. It has in my all cases succeded with 100%!
I have also noticed one more thing: There is a Connection between fine sand(up to around 1 mm) and more dino. In an aquarium with mixed sandbed i noticed that there was no dino in the bed with grain size over 2 mm, all the dinos was in the sugarsand. After that i swithed to grain size around 2-5 mm and i have had no dinos since.

I agree with almost Everything. I have struggled with dinos 7 times, and tried Everything. My brief conclusions is:
1)Algenex works, but the dinos will often be back and the corals suffer some from algenex.
2) cut off the light works but only for the moment. it will be back
3) Probiotica does not work
4) Rising ph is difficult and has no clear effect. I have red some studies that tell the counterpart but i doubt...

The only cure i succeded with is to eliminate all the sand, as it Always start there. Then, rinse the sand in H20 ands replace after one week. It has in my all cases succeded with 100%!
I have also noticed one more thing: There is a Connection between fine sand(up to around 1 mm) and more dino. In an aquarium with mixed sandbed i noticed that there was no dino in the bed with grain size over 2 mm, all the dinos was in the sugarsand. After that i swithed to grain size around 2-5 mm and i have had no dinos since.

I can throw the opposite out. My sandbed was 2-5mm and I had dino. I removed it and the Dino just moved to the rocks.

I think only certain types of Dino are affected by cure X. High PH seems to kill some types of Dino. I think the proper way to tackle them is to try multiple things and maybe even go down a list of things to try in a certain order (from easiest to hardest or maybe risk).

For instance. X notices dinoflagellates.

Lowest Risk:
1) Stop Water Changes
2) Add Pods and feed phyto
3) Lights Outs for 3-4 days
4) Siphon Sand bed
4) If this is positive do the same thing 1-2 times a month until Dino is gone

High Risk:
1) Dose H2O2 at X rate while lights out
2) Keep Lights out for 3-4 days and continue daily dose of H2O2
3) Remove Sandbed

Thats why I think it would be nice for someone who is smarter than me to write up a Article about dino and list out a plan to tackle them. Show all options (UV, H2O2, pods, Bacteria additions, No Water changes, lights out etc....). The article should also go into identification and how it is believed that they can work with Cyano. Explain a microscope is a sure way to ID it and show examples of different types along with Dino/Cyano blends.

natas, you have to remove very very carefully ALL sand, every grain...wait one or two weeks...AND if you already have some one the rocks this is not sufficient as you say. According to my experience dinos nearly almost start at the sand, so if you do not wait to it go to the rock, you can eliminate it with sand extraction. But, it is very important to take everything out and that is not so easy. concerning grain size it is a "medium risk" maybe, so of course you can get dino in that grain size, but in my tanks it has come much faster with more fine sand.
Algea X has not worked for me, maybe because different dinos as you say, but Algenex is frequently used in Sweden with almost always 100% success, BUT big recurrence rate!..

I promise you...let me struggle an aquarium with dino only in the sanded and i will get rid of it. It is the only way that really worked for me, and the aquarist i have helped the last year. But i cannot enough stress, that this is not the true if you have it on the rocks. The you have to remove the rocks and clean them off in saltwater, and then observe carefully, and wait to introduce sand to you cannot see anymore dinos.

All these methods have been tried and tested several times. Dino's are never gone, just kept in check by some mysterious boundary. The most knowledgable scientists can't tell you how to completely eradicate them, so I am more then a little sceptical. Unless you have been without Dino's for 12 months, I don't consider you Dino free.

@jonasroman My experience with sandbeds mirrors yours. My dinos aren't on the sand much at all, they prefer the glass and rocks. Siphoning my sandbed actually made them worse. This may be species dependent, we just don't know.

@natas I've been fooling with a summary/flow chart sort of thing for identifying dinos. I tried to make a graph of all the methods of kill mentioned in this thread, but it's not going to be possible. Single methods tend not to work, and I am becoming certain that different genera have different vulnerabilities. Also I can't figure out how to make a chart comparing various groups and multiple methods.

tldr version: first things I'd try (all of these at the same time): stop water changes, pull chemical filtration except carbon, siphon what you can, run skimmer very wet, add a lot of carbon and do a 3 day lights out. Add filter socks or as much mechanical filtration as you can. I use cheesecloth in my aio. You'll need to change the socks at least daily, more during lights out.

It's very important to skim and run carbon during lights out. Longer lights out knock dinos back, but rarely kill them off completely. Lower photoperiod doesn't seem to have any effect either.

2nd step is probably: You want measurable nitrates, ~1 or 2, and phosphate around 0.03. (Less nitrate in an SPS tank) Add a lot of biodiversity, dose phyto, feed as many kinds of foods w different particle sizes as you can afford, stop skimming, pull all chemical media except carbon. If you have a reactor, try raising pH to 8.4 (If you don't it's nearly impossible unless you're home to add kalk on the hour)

3rd step: technology and chemistry

hth
ivy

biodiversity: pods from different sources (try to get benthic pods or a mix of copepods, amphipods, isopods etc), macroalgae, rocks, sand from fellow reefers, skimmate from someone with a good tank (yes, really), detrivore or maintenance kits from IPSF, reefcleaners, tbs

All these methods have been tried and tested several times. Dino's are never gone, just kept in check by some mysterious boundary. The most knowledgable scientists can't tell you how to completely eradicate them, so I am more then a little sceptical. Unless you have been without Dino's for 12 months, I don't consider you Dino free.

What strain of Dino's did you have.

I do not know the strain but for sure it was dino, and it was around 11-12 months ago i had it last. I tried exactly everything, then worked with the theory that it emanate from the sand, and preferably sugarfine dito(not always), so i tested my theory and it worked for me, and for two other aquarist i helped. As in this complicated world i cannot guarantee that it helps everyone of course, just telling my experience and struggling with dino, which over the years are the last 7 years at least. it is very important to take almost every grain out...that mistake have i done, leaving some grains, then it did not work.

That is good to hear as I've read all your posts which got me started on adding more diversity to the tank.

It's been 1.5 weeks since stopping peroxide dosing for me and I am dino free so far. I did 2 weeks of peroxide/2-day complete blackout, no water changes/skimming. After the peroxide I setup chaeto w/light in my sump and added pods, as well as building up my CuC more. Also have microalgae on the way. On top of all that I've been overfeeding and using frozen food, broadcasting coral frenzy, etc. It's weird because my tank has never looked so clean!!

That is good to hear as I've read all your posts which got me started on adding more diversity to the tank.

It's been 1.5 weeks since stopping peroxide dosing for me and I am dino free so far. I did 2 weeks of peroxide/2-day complete blackout, no water changes/skimming. After the peroxide I setup chaeto w/light in my sump and added pods, as well as building up my CuC more. Also have microalgae on the way. On top of all that I've been overfeeding and using frozen food, broadcasting coral frenzy, etc. It's weird because my tank has never looked so clean!!

Congrats, that's good to hear, I kept my skimmer off until hair algae started on the back glass, it cleared up soon after restarting the skimmer.

Is it just cost that drives a preference for the dirty method over the clean method?

I disagree.

UV has pros and cons.
The water column gets pristine because the UV kills all the plankton in it.
High power UV and max efficiency with slow flow is certain to leave nothing alive coming out of it.
It's use on reef health has been debated for decades and I have nothing to add to that.

I'm glad it seems to have worked for you but what happens when you turn the UV off for a week or two?

The water column isn't pristine. I have more plankton in this tank than I've had in any other. At night, I shine a flashlight into the water and I see a cloud of reflective creatures wriggling towards the light source. I have multiple videos of broods of shrimp nauplii, pods and fish fry.

It has nothing to do with the UV. Dinos are free floating at night and I zap enough of them that they cannot win. I zap others too but it's slow enough that the rest of the plankton that's alive feeds on the dead. It's no different than adding one big plankton predator... It just keeps them in check without destroying the population.

Most of my plankton is likely juvenile stages of benthic adults. So, the parents continue to pump babies and some don't make it. It doesn't kill the chain. More babies keep coming.

What did the most damage to the dinos was the three days of dark with UV. They had nowhere to be safe. They were exterminated along with some good guys. But the base of plankton didn't die. It just got a massive advantage.

By the way, the single biggest reason I have so much plankton is the absence of mechanical filters - no socks, no sponges, no bags. These are the real plankton killers. They destroy the mid tier plankton base and turn their bodies into local waste for bacteria and dinos to feed on. If you clean them often, that's good housekeeping and avoids bigger problems but it's just another way to throw plankton away.

DInos are no longer on sand bed, but on rocks. Red Slime is growing on two of my corals (Acans). How should I go about cleaning them? Water change? I haven't done a water change in 3 - 4 weeks. Should I do chemi clean? I did chemi clean last time and dinos exploded (I think). Not sure what to do

Originally Posted by BigJohnny View Post
For everyone running/who ran the dirty method, how high did your nitrates and PO4 get and did you lose any sps corals?

Quote:

Originally Posted by BigJohnny

Anyone have experience with this?

BigJohnny, I just thought of this as well. I've been running dirty method for months now and kept worrying about the same. I dont have any SPS to worry about but I wanted to test NO3 and PO4. I was SURE they're be off the charts. What did I find to my surprise?

NO3 = 0.1
P04 = 0.00

I've been overloading with food, no water changes, no skimming for months. I do have a functioning DSB that I give credit to the low NO3